Proxy server can act as an intermediary to in computer networks to route a network request (e.g., a Hypertext Transfer Protocol (HTTP) request or a Session Initiation Protocol (SIP) request, etc.) from a communication endpoint. As used herein, “communication endpoint” can be any client device that is capable of transmitting and receiving data over the computer networks, such as a personal computer (PC), a laptop, an IP (VoIP) phone, a mobile phone, etc. A communication endpoint seeking a network resource can transmit a network request to a server that provides resources. The communication endpoint can include in the request information specifying a server for forwarding the request after the communication endpoint receives network resources from that server. For example, each of Request For Comments (RFC) 2109 and 3261 provided by Internet Engineering Task Force (IETF) for HTTP and SIP requests, provides mechanisms for a server to pass routing information that represents a state of the connection (e.g., cookie) to the communication endpoint. The routing information can include the network location information (e.g., an IP address, a port number, etc.) of the server. The communication endpoint can store the routing information as state information. The communication endpoint can also retrieve the routing information from the stored state information and include the retrieved routing information in a subsequent request for network resources. A proxy server can then forward the subsequent request to the server.
However, at the time when the proxy server receives the subsequent request from the communication endpoint, the routing information may become invalid. For example, it is possible that an event has occurred during the time between the first request (from which the communication endpoint receives the routing information) and the second request, such that the proxy server can no longer use the network location information included in the request for forwarding the request.